Power cut-off



May 9, 1933. P. R. HORNBROOK POWER CUTOFF Filed Feb. 24-. 1930 INVENTOR pH/L/ E-HOPNBEOOK ATT RNEY Patented May 9, 1933 UNITED STATES raianrflorrica R. HORNIBBOOK, OF ALLEN'IOWN', PENNSYLVANIA, ASSIGNOR '10 FULL-BRUCE" rm, O1 GATASAUQUA, PENNSYLVANIA, A CORFEORATION OF DELAWARE POWER GUT-0F? Application filed February 24, 1:930. SeriatNo. 430,533.

This invention relates to power cutoffs or mechanically operated switches for the purpose of stopping a driving motor when a driven machine or element thereof decreases in speed below a predetermined rate, or stops for more than a predetermined short interval.

The invention has particularly to do with a mechanically driven, dust-proof switch of simple construction and positive operation for the purpose ofpreventing harmto elements of a machine, or machines operating in combination, due to failure of one element to operate properly.

In general the invention'comprises a container in which a paddle wheel is arranged to be driven externally from a part of a rotating device which must be kept in opera- ,tion to prevent injury to another part of the apparatus. The paddle wheel causes a flow of oil or other fluid in a continuous circuit around the lower portion of the container. A movably supported switch is provided with a vane or similar element pro'ecting into the path of the fluid," whereby t e switch may be held in the desired position due to the pressure of the fluid against it.

In. the preferred embodiment of my invention, the switch is of the mercury tube type and its support is arranged within the container and pivoted to move within desired limits. The paddle wheel may be suitably driven by a. culation and the switch in closed position, for instance, during operation. In this case, the circuit is preferably closed through the contacts of the switch to the controlling device of a motor which operates the apparatus or an element of it.

If the speed of rotation of the element from whichthe paddle wheel is driven decreases, but remains within safe limits, the switch ma be kept in closed osition and likewise be hept closed if the riving element stops momentarily. If, however, the speed falls below a safe limit, or the device stops for more than a short interval, the momentum of the fluid will decrease sufliciently to cause the switch to move to its open position due to the decrease in pressure against the vane. If the paddle wheel stops momentarily, the

beltto keep the oil in cirmomentum of the oil will keep the switch in closed position for short intervals.

In order to cause the switch to return to open position when the speed of the moving element decreases below a safe limit, or stops for longer than a safe interval, but to kee the switch closed for intermediate higher speeds and shorter stoppages, I have provided a movable counterweight for the support, so that the switch may be adjusted to operate when the rate of flow of the fluid decreases correspondingly.

My invention may be used in combination with conveying apparatus in which the material to be transported is handled by separate conveying or feeding devices, having a common or separate driving motors. In this arrangement, a momentary stoppage or a de crease in speed of one of the conveying elements may not cause harm, but a stoppage for a longer interval, or a decrease below a certain speed might cause mechanical damage to other elements, overflow of material or a dust nuisance. In this case the power cutoff in accordancewith my invention is driven by an element, the proper operation of which is essentialto the operation of the related apparatus. The switch may be connected to.

a warning signal or arranged to interrupt the operation of a motor driving the apparatus or related equipment. I

For a better understanding of my invention, reference is made to the accompanying drawing, in which:

Fig. l is a diagrammatic illustration of a s5 conveyor for handling grain or similar material by suction in which my invention is embodied;

Fig. 2 is a plan view of the switch with the cover removed;

Fig. 3 is a vertical section through the switch on line -IIIIII of Fig. 2.

Fig. 4 is a side elevation of the switch with the side walls of the container and outlet broken.

Fig. 5 is a section through the feeder at the discharge end of the hopper.

Referring to the drawing and first to Fig.

1, the invention is shown in combination with a pneumatic conveyor for handling grain or 100 similar material. The grain is drawninto a collector 5 having a hopper bottom 6, through a conduit 7, the collector being exhausted through pipe 8 by the exhauster or pump 9.

The exhauster is indicated as being driven by a. motor 10 through a belt 11.

switch 20. When the switch lever 21 is in closed position it is held in place by electroma ets 22. The electro-magnets are inclu ed in a circuit 23 and 24 and the power cutofi switch 25, to be described in detail hereinafter.

The power cutofl switch comprises a casing 26, in which a paddle wheel 27 is driven throu h an external shaft 28 and pulley 29, suitab y belted to the feeder shaft. Below the level of the shaft 28, the casin is rovided with a quantity of oil or other 1qui 30 which flows in a continuous circuit around the interior of the lower portion of the casing 26 and is deflected by the baflle 31. The support 32 serves as a base for a mercury switch 33 of usual construction and which is provided with contacts 34 and 35 to which the leads 23 and 24 are connected. In the present embodiment of the invention, the switch 33 is shown in its closed position through the mercury 36 to complete the circuit through the electro-magnets 22 to keep the motor control 20 in closed position.

The support 32 is pivoted at 28 and moves between t e stops 39 and 40. The switch is held in its closed position by pressure of the oil 30 against the vane 41. A counterweight 42 serves to counterbalance the weight of the switch and its support and also to make the switch responsive to various oil pressures. When the support is substantially in balance, a ve slow movement'of the oil will move the switc into closed position, and as the weight is moved inwardly toward the support, more rapid oil flow is necessary to move the switch;

The operation of the apparatus is as follows: When the circuit to the motor 10 is closed through the switch 20 and the apparatus is brought to operating speed, the paddle wheel 27 causes the oil to flow in the direction of the arrows shown in Fig. 2. The pressure of the oil against the vane 41 tilts the latter and completes the circuit through the electro-ma ets 22 to hold the switch 21 in closed position during normal 0 ration.

. Should the speed of rotation of t e feeder 12 decrease due to drive trouble or entrance of foreign material, but continue to discharge.

the grain fast enough to prevent the accumulation of increasing quantities in the hopper 6, there would be no necessity for stopping the motor 10. Likewise the exhauster 9 should be kept in operation if there is only a momentary sto age of the feeder. In eit er case the rate 0 flow of the oil 30 will provide suflicient pressure against the vane 41 to maintain the switch 33 in closed position. By adjusting the counterweight inwardly to the proper point, the switc can be ad usted to open when the feeder 12 stops or decreases 1n speed below a safe or desired rate.

Although I have shown and described the apparatus with a single motor for driving two related driven devices, it is to be understood that independent drives can be used and that the operatlon of one of the elements can govern the operation of a number of others.

have shown the device in a direct current circuit, for simplicity, but the switch can be used equally well to control alternating current motors, button circuit of magnetic starters or in the low voltage circuit of manually operated starters.

I claim: a

1. A switch comprisin the combination of a container, a paddle w eel within thecontainer and having a drive shaft extendin through a wall thereof, a quantity of liquid within the lower portion 0 the container to be set in motion in a continuous course by the paddle wheel, a pivotally mounted support, an electric switch secured to the su port and means to move the su port comprislng a vane extending downwar y into contact with the liquid.

2. A switch comprising the combination of a container, a paddle wheel within the container, havin a drive shaft extending through a we of the container, a uantity of fluid within the lower portion 0 the container to. be set in motion in a continuous course by the paddle wheel, a pivotally mounted 'sup rt having a vane extending downwardly into the course of the fluid to move the support by pressure of the fluid and a switch mounted uppn the support and actuated by movement t ereof. 3. A switch comprisin a container, a paddle w tainer, havinlg through a wal of the container, a quantity 0 liquid within the lower portion of the contamer to be set in motion in a continuous course by the paddle wheel, a pivotally mounted support having a vane extending downwardly into .the course of ftlig liquid to move t e su port y pressure 0 e movin liquid, an adiustable counterweight arranged on the support to re cordance with p the combination of eel within the conate its movement in acetermined pressures and as it may be placed in the stop a drive shaft extending on the support and actuated by movementthereof.

an electrical switch mounted on the support and actuated by movement thereof.

4. A switch com ris' the combination of a container, a pa dle v iifieel within the container,

liq d within the lower portion of the contamer to be set in motion in a continuous course by the paddle wheel, a mounted support having a vane extending downwardly into the course of the liquid to move the su port by pressure of the movin liquid, an mfiustable counterweight arranged on the support to lzgulate its movement in accordance with pr eterminedpressures and a switch of the mercury tube type mounted pivotally 5. A switch comprising the combination of-a container, a uantity of liquid within the lower portion 0 the container, externally driven means within the container for moving the li uid in a continuous course therein, a pivots y mounted support, an electric switch of the mercury contact type secured to the support, the support havin an element extending downwardly into the course of the liquid and responsive to the pressure of the moving 1i uid to move the su close the switc and means to regulate the movement of the support in accor ance with predetermined pressures to cause the switch to move to'open position after the speed of rotation of the externally driven means falls below a desired rate.

In witness whereof I have signed this spec I PHILIP R. HORNBROOK.

ification.

having a drive shaft extending through a wall of the container, a quantity 0 pport to' 

